Re: [CAD_CAM_EDM_DRO] CNC Closed Loop Control??

p0p0k0pf wrote:

>This is my first post here and I have a question!
>
>I plan on installing DRO and CNC on my Shoptask Eldorado
>Drill/Mill/Lathe, and i was thinking...
>
>Is there such a thing as closed-loop CNC control, where CNC step
>input is based on the output measurement on DRO scales?
>Theoretically, this would eliminate or check any backlash or step-
>jump issues...
>
>

Yes, there certainly is. This can be used with servo motors, or with
steppers. Very
few software packages have the direct position feedback to the CNC
computer, however.

>I like CNC for all its attributes, but I like DRO for it's absolute
>measurements...it seems like combining the two separate systems would
>be the best choice.
>
>

EMC is fairly good at doing this, although there are some functions that
are blocked when
in E-stop - which would become your DRO mode. But, it can pretty easily
jump between
estop and running mode.

>I am no programmer or electronics expert, so I have no way to go into
>further details, but does anyone have any ideas on the matter?
>
>

I have 2 products that support closed-loop CNC control from the PC. See
http://jelinux.pico-systems.com/PPMC.html for these units. Ot this
page, there is
a link to "Universal Stepper Controller" which is the lower cost
alternative for
stepper-based systems. It can be used either open-loop or closed-loop.

Jon